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What’s needed for healthy soils?

By Staff | Feb 18, 2017

DOUG PETERSON, an Natural Resources and Conservation Service regional soil health specialist for Iowa and Missouri, performed this experiment in front of a near-capacity crowd at a soil health/cover crops workshop Feb. 7 in Spirit Lake. Above, he places dirt clods — one from a tilled field and one from a no-till field — into tubes holding water. The demonstration shows the difference between soil densities and the likelihood of soil erosion in a rain situation.

SPIRIT LAKE – Farmers have learned over time that they farm “by the seed and not by the acre.”

Going with that same principle, producers are encouraged to improve soil biology, which would include reducing, or even eliminating, commonly-used tillage practices.

This was the message heard at a Feb. 7 soil health/cover crops workshop in Spirit Lake, sponsored by North Central Sustainable Agriculture Research & Education, Iowa Farm Bureau and the federal Natural Resources and Conservation Service.

Doug Peterson, regional soil health specialist with NRCS, told a near-capacity crowd that water erosion is a serious problem, adding that if soil maps were to be re-made in Iowa, up to 60 percent of the state would not have the same soil type as the original map showed.

Peterson showed an example of water-holding capacity as he dropped dirt clods into graduated cylinders filled with water.

AFTER PLACING THE CLODS in the water, Peterson showed that soil is much less dense in a field that has been tilled (in the dirt-blackened tube), showing a likelihood of water run-off and soil erosion during a rain situation. The dirt clod in the clearer tube — from a no-till field — remained intact, showing soil in that situation is more likely to remain where it is, and that water running off of the field would not take as much, if any, top soil with it.

One was from a tilled field and the other was from a no-till field two miles away. Both were the same soil types. The tilled sample fell apart as water rushed into it, leaving water murky, while the no-till sample remained in one piece, the water around it remaining clear.

“It’s not about how much rain you get,” he said. “It’s about how much rain you keep.”

Peterson said soil biology is more important now than ever with the seriousness of water erosion. He said maintaining topsoil and keeping nutrients is the only way to keep farm land sustainable.

And in order to do that, soil aggregation must first happen.

Peterson said this includes keeping roots in the ground all year to help supply soil with nutrients that are emitted from them, along with the “glues” emitted from soil bugs that hold it together in a rain situation.

Earthworms burrow into the soil and secrete slime, which lessens the worm’s energy needs. Both of those enzymes emitted from plant roots and worm slime give off a biotic glue, which helps soil hold together.

Peterson said soil sticks to roots, and the plant gives off enzymes to make nutrients available. In turn, it attracts biology to bring them nutrients.

He added microscopic bugs live in the soil and help with decomposition of plants, but when that decomposition is finished, the bugs “go away” if there is nothing else to feed on.

“Plant roots can be very specific,” Peterson said.

He said the less soil is disturbed, the more healthy soil organisms and bugs, bacteria and fungi can live in it, bringing nutrients back to the soil and also to plant life that is there keeping the soil healthy.

“Soil is alive and we need to keep it healthy,” he said. “We need to put as much thought, planning and effort into feeding our soil organisms as we do feeding our row crop production.”

He said roots grow deep and can bring valuable nutrients from a few feet deep to the top of the soil profile where seeds are planted. Peterson said if there are no roots, the soil biology dies or goes dormant.

Peterson said letting cows forage on corn ground adds about $100 per acre value with their contribution to the soil profile of manure, saliva and milk foam.

Nitrogen mineralization and immobilization is important and involves having enough substance in the soils for bugs to eat all year so the soil remains healthy for the long-term.

“You have to tie into (keeping the nitrogen you already have) – that’s dollars,” he said, adding that not taking care of nitrogen opportunities already in the soil is like taking a $50 bill and throwing it away on every acre. “It costs $20 to $30 to plant a cover crop.”

Peterson said weed control is important, but more importantly, not letting weeds get started in the first place is key. Cover crops can help that, he said.

Getting a witness

Loran Steinlage, of West Union, was one of two row crop producers who explained his use of cover crops.

Steinlage has used cover crops since 2009.

He said his soil health improved over time as he made adjustments to his equipment and planting/tillage procedures.

Soil carbon is key, according to Steinlage, adding, “$15 per acre in seed equals 15 bushels per acre.”

Steinlage plants his own cover crops with implements he innovates on his farm. He said with cover crops, his ground is warmer in the spring, cooler in the summer and warmer in the fall as temperatures begin to cool off.

He added he plants beans into standing cereal rye and still gets 40 bushel beans and 40 bushel rye, without inputs. He said his long-term goal is to be able to harvest two cash crops off one field.

Shenendoah farmer Chris Teachout showed the value of cover crops on ground temperature with a photo. He took a photo of sensor readings that showed the ground temperature being 93 degrees at the 4-inch level and the surface temperature of the ground being 140 degrees.

“Soil biology stops (goes dormant) at 80 degrees,” said Peterson, illustrating the value of keeping ground covered so it does not overheat.

Teachout said he harvested 69 bushels per acre soybeans, spraying cereal rye the day after he planted those soybeans. He said cereal rye can begin growing at 38 degrees, and that keeping ground at a more constant temperature helps plants. Teachout added biological activity in the soil creates heat and keeps soil warmer in cold months.

He said when he tilled his fields he had 2 percent soil organic matter, and now with cover crop usage it shows 3.4 to 5.6 percent.

Steinlage said if nitrogen and other nutrients are leaching, they can’t be caught without roots in the soil and good soil aggregation.

“We need to capture it and use it,” he said, saying farmers need to utilize the nutrients they already have before purchasing more to apply, to help the bottom line. “I can tell it in my yield efficiency.”

“We’ve seen $3 corn, but I’m ready for $1 corn.”

Farmer panel

Four Northwest Iowa farmers made up a panel to explain what they do and answer questions about their tillage practices and cover crops.

One of them, Denny Winterboer, of the Fostoria/Milford area, said he tracks earthworm life in his soil and he’s convinced they help him aerate the soil and help with soil aggregation.

“Earthworms lay eggs, which I didn’t know before I started this,” he said. “But every time you go down through a field with tillage equipment, you disturb that biology – earthworms die and the eggs disappear.”

Winterboer encouraged producers to do as little tillage as they can get away with.

“If you can, only till right where you have to plant,” he said.

NRCS officials state that eliminating tillage minimizes the loss of organic matter, reduces the impact of compaction and protects the soil surface with plant residue.

NRCS said most farmers can increase soil organic matter in three to 10 years if they are motivated to adopt conservation practices to achieve that goal.

John Boettcher, of Spirit Lake, said he’s in his fifth year of cover crop usage and said he has seen success with it.

He plants cover crops by plane and grazed his land more extensively this past fall than he has in previous falls.

“I will be anxious to see how it comes back in the spring,” he said.

Jared Herbert, of Lake Park, has used aerial-seeded cover crops for the past seven years with good results, adding that there could be a better way to apply the seed.

He said he still does his share of experimenting but encouraged producers to seek out others who have been working with cover crops.

“A person doesn’t live long enough to learn everything by himself,” he said. “If you do, you’re going to get behind.”

Winterboer said he conducted a soil density test, which taught him about the differences in the soils in tilled and no-tilled ground and even in the soils around the fence lines.

He found the numbering system effective in managing soil health across the board.

“You have to be able to number it in order to manage it,” he said.

Winterboer added soil that has been cared for can hold a lot of water – even a lot of water in a short period of time, eliminating runoff and retaining soil nutrients.

Mike Henderson, regional NRCS representative, urged producers to run trials on their farms regarding the usage of nitrogen applications and to start calibrating the biology on their farms.

“You need to go field by field,” he said, “don’t use a blanket approach.”

“We’re heading for sustainability … so we need to use the measuring tools we have to categorize our farms as sustainable. That’s where we’re going in the future.”

Producers considering planting cover crops must discuss it with their crop insurance agent to come to an understanding about coverage policies.

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